AUTHOR=Fernandes Maria Aparecida , Cioffi Marcelo de Bello , Bertollo Luiz Antônio Carlos , Costa Gideão Wagner Werneck Félix da , Motta-Neto Clóvis Coutinho da , Borges Amanda Tôrres , Soares Rodrigo Xavier , Souza Allyson Santos de , Pinthong Krit , Supiwong Weerayuth , Tanomtong Alongklod , Molina Wagner Franco 

TITLE=Evolutionary Tracks of Chromosomal Diversification in Surgeonfishes (Acanthuridae: Acanthurus) Along the World’s Biogeographic Domains

JOURNAL=Frontiers in Genetics

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2021.760244

DOI=10.3389/fgene.2021.760244

ISSN=1664-8021

ABSTRACT=<p>Fishes of the genus <italic>Acanthurus</italic> (Acanthuridae) are strongly related to reef environments, in a broad biogeographic context worldwide. Although their biological aspects are well known, cytogenetic information related to this genus remains incipient. In this study, <italic>Acanthurus</italic> species from populations inhabiting coastal regions of the Southwest Atlantic (SWA), South Atlantic oceanic islands (Fernando de Noronha Archipelago and Trindade Island), Greater Caribbean (GC), and Indo-Pacific Ocean (the center of the origin of the group) were analyzed to investigate their evolutionary differentiation. For this purpose, we employed conventional cytogenetic procedures and fluorescence <italic>in situ</italic> hybridization of 18S rDNA, 5S rDNA, and H3 and H2B-H2A histone sequences. The Atlantic species (<italic>A. coeruleus, A. chirurgus</italic>, and <italic>A. bahianus</italic>) did not show variations among them, despite their vast continental and insular distribution. In contrast, <italic>A. coeruleus</italic> from SWA and GC diverged from each other in the number of 18S rDNA sites, a condition likely associated with the barrier created by the outflows of the Amazonas/Orinoco rivers. The geminate species <italic>A. tractus</italic> had a cytogenetic profile similar to that of <italic>A. bahianus</italic>. However, the chromosomal macrostructures and the distribution of rDNA and hisDNA sequences revealed moderate to higher rates of diversification when <italic>Acanthurus</italic> species from recently colonized areas (Atlantic Ocean) were compared to <italic>A. triostegus</italic>, a representative species from the Indian Ocean. Our cytogenetic data covered all <italic>Acanthurus</italic> species from the Western Atlantic, tracked phylogenetic diversification throughout the dispersive process of the genus, and highlighted the probable diversifying role of ocean barriers in this process.</p>